Cambridge A-Level Biology 9700 – Conservation: Controlling Invasive Alien Species
Conservation – Controlling Invasive Alien Species
1. Introduction
Invasive alien species (IAS) are organisms introduced, intentionally or unintentionally, into habitats where they are not native. Once established, they can spread rapidly and cause ecological, economic, and social problems. Effective control is a key component of biodiversity conservation.
2. Impacts of Invasive Alien Species
The following table summarises the main types of impact caused by IAS.
Impact Category
Examples
Consequences
Ecological
Predation, competition, hybridisation
Loss of native species, altered food webs, reduced genetic diversity
Economic
Crop pests, livestock parasites, damage to infrastructure
Increased management costs, loss of agricultural productivity
Human Health
Vectors of disease, allergenic plants
Increased disease incidence, health care costs
Social & Cultural
Loss of culturally important species, reduced recreational value
Diminished ecosystem services, impact on tourism
3. Reasons for Controlling Invasive Alien Species
Control measures are justified for several inter‑related reasons:
Preserve native biodiversity: Prevent extinction or decline of indigenous species.
Maintain ecosystem function: Protect processes such as pollination, nutrient cycling, and habitat structure.
Protect economic interests: Safeguard agriculture, fisheries, forestry, and tourism from loss and damage.
Reduce health risks: Limit the spread of disease‑bearing organisms and allergenic plants.
Uphold legal and ethical obligations: Many countries have legislation requiring management of IAS and international agreements (e.g., CBD, IUCN).
Prevent irreversible changes: Early intervention is often cheaper and more effective than later eradication attempts.
4. Approaches to Control
Control strategies can be grouped into three main categories:
Prevention: Quarantine, border inspections, public awareness.
Early Detection and Rapid Response (EDRR): Monitoring programmes, rapid eradication when populations are small.
Long‑term Management: Mechanical removal, chemical control, biological control, habitat restoration.
5. Case Study – The American Mink (Neovison vison) in the UK
The American mink was introduced for fur farming and escaped into the wild. Its impacts include predation on water voles and ground‑nesting birds.
Control method: Trapping programmes combined with habitat enhancement for native species.
Outcome: Local reductions in mink numbers have led to measurable recoveries of water vole populations.
6. Summary
Controlling invasive alien species is essential to protect native biodiversity, maintain ecosystem services, and safeguard economic and human health interests. Effective management relies on a combination of prevention, early detection, and targeted control measures, supported by legislation and public engagement.
Suggested diagram: Flowchart showing the decision‑making process for invasive species control (prevention → detection → rapid response → long‑term management).